During World War II, Gallagher commanded an infantry rifle company in General George S. Patton's Third Army in Europe.

He was elected to the Hudson County Board of Chosen Freeholders in 1953, a post he held until resigning in 1956, when he was appointed commissioner of the New Jersey Turnpike Authority.

[2] Gallagher subsequently became vice president of Baron/Canning International in New York City, and was a resident of the Columbia section of Knowlton Township, New Jersey.

[4] Gallagher was a critic of the tactics of Federal Bureau of Investigation Director J. Edgar Hoover and Attorney General Robert F. Kennedy.

[5] Media accounts then surfaced, including Life magazine,[4] which contained alleged leaked material from FBI wiretaps suggesting that Gallagher was connected to the mafia, Gallagher accused Hoover of fabricating the stories to hound him from public life.